Lithium Battery Electrode Surface Roughness Control
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Solution Overview
Problem
Current rechargeable lithium batteries face limitations in cycle life characteristics, which are essential for maintaining high performance in portable digital devices, despite their high power and energy density.
Innovation Solution
The rechargeable lithium battery addresses this by controlling the surface roughness of the positive and negative electrodes within specific ranges (arithmetic average surface roughness of 155 to 419 nm for the positive electrode and 183 to 1159 nm for the negative electrode), using nickel-based active materials and a non-aqueous electrolyte with lithium salts, to enhance cycle life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rechargeable lithium batteries use conventional electrode structures, then high power and energy density are achieved, but cycle life characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness of electrodes within specific ranges (Ra 155-419 nm for positive electrode, Ra 183-1159 nm for negative electrode). This parameter optimization resolves the contradiction by improving cycle life characteristics while maintaining the battery's high power and energy density performance over extended periods.
2Reliability
If electrode surface roughness is not controlled, then manufacturing simplicity is maintained, but cycle life characteristics worsen
Solution Approach 1:
The patent establishes specific surface roughness parameter ranges for electrodes that can be achieved through conventional manufacturing processes. By defining Ra 155-419 nm for positive electrodes and Ra 183-1159 nm for negative electrodes, the invention improves cycle life without requiring complex or expensive manufacturing modifications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively improves the cycle life characteristics of the lithium battery, as demonstrated by increased capacity retention and reduced surface roughness, leading to improved battery performance over repeated charge and discharge cycles.
Implementation Method 1
a positive electrode that has a positive active material which is capable of reversibly intercalating and deintercalating lithium ions
Implementation Method 2
an electrolyte
Data Source
AI summary
A rechargeable lithium battery includes a positive electrode having a positive active material to reversibly intercalate and deintercalate lithium ions, a negative electrode having a negative active material, and an electrolyte, wherein an arithmetic mean Ra of a surface roughness of the positive electrode is 155 to 419 nm, and an arithmetic mean Ra of a surface roughness of the negative electrode is 183 to 1159 nm after the rechargeable lithium battery is charged and discharged.